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Compaction, Excavation and Earthwork Publications Available for Downloading

Detailed specifications and guidance can be found at your local State
Department of Transportation Specifications for Roads and Bridges. Some of these principles
may apply to building structures, retaining walls and slope stability. Most State Departments have
a wealth of information on-line. See calculations for compaction, earthwork
and phase diagrams below:

COMPACTION

Example #1: A project requires fill to be
compacted to 95% relative density with relation to the standard Proctor
(ASTM D698). Laboratory results for the standard Proctor indicated that the
soil has a maximum dry density of 19.0 kN/m3 (121 lb/ft3),
and an optimum moisture content of 8.9%.

After compaction of the fill soils with a vibratory roller, field
testing with a sand cone, nuclear densiometer, or other appropriate method
indicated that the compacted fill soils have an in-place unit weight of
18.76 kN/m3 (124.4 lb/ft3), and a moisture content of
7.5%. Calculate the relative compaction, and does the compacted fill exceed
project requirements?

Example #2: A project requires fill to be
compacted to 100% relative density with relation to the standard Proctor
(ASTM D698). The fill has been vigorously compacted to a relative density of
96.9%. Subsequent compacting does not increase the relative density. What
could be the problem?

Solution

1) Check the moisture content of the compacted fill. Depending on the
soil type, an in-situ moisture content deviating 2% to 4% from the optimum
moisture content as determined from the Proctor test, may create impossible
conditions to achieve the required compaction. If this is the case, scarify
soil and add moisture (or let dry), and re-compact at the optimum moisture
content. Sometimes, complete removal and replacement of the soil is
necessary.

2) Verify the maximum dry density as determined from the Proctor test
still holds true for the 'un-compactible' soils.
Sometimes the maximum dry density changes as different soils are excavated
from the borrow pit. If this is the case, use the new maximum dry density
value when determining the relative density.

3) Check compaction methods. Type of equipment used for compaction and
the depth of compacted lifts make a difference in the relative compaction.

4) Check for inadequate compaction in underlying lifts. Sometimes
achieving adequate relative density is impossible when compacting soils on
top of loose or unconsolidated soils.

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EARTHWORK/ COMPACTION/ PHASE DIAGRAM

Example #3: This is in part, a phase diagram
problem. A project requires fill to be compacted to 95% relative density
with relation to the standard Proctor (ASTM D698). Laboratory results for
the standard Proctor indicated that the soil has a maximum dry density of
19.49 kN/m3 (124 lb/ft3), and an optimum moisture
content of 9.5%. Borrow soil from another location that will be used as
compacted fill for this project has a moisture content of 12%, a void ratio
of 0.6, and a specific gravity of 2.65.

Assuming that no moisture is lost during transport, what is the volume
of borrow required that is needed for 28.32 m3 (1000 ft3)
of compacted fill?

The volume of soil required from the borrow pit is 32.3 m3
(1140 ft3). Equations used for this problem are standard phase
diagram relationships shown here. Other
phase diagram equations may be required depending on the situation.

COMPACTION

Below are a few powerpoint presentations that you can download. The original author of
these powerpoints is unknown. The original versions were slightly edited afterwards.